Major League Baseball is going to brand the bases, pitcher's mound and on-deck circle in ballparks with advertisements for the movie "Spider-Man 2," angering some purists who believe creeping commercialization is dishonoring the national pastime and other historic sporting events.

The promotion will occur during games on June 11-13 and mark the latest encroachment of advertising from traditional locations such as billboards to direct product promotion on the playing field, on game equipment and even on uniforms.

A Kentucky judge last week ruled that jockeys could break a century-old tradition at the prestigious Kentucky Derby at Churchill Downs and begin wearing advertising on their shirts. Earlier this year, the New York Yankees and Tampa Bay Devil Rays placed sponsor patches on their caps for baseball's season opener in Tokyo.

"It's inevitable but awful," said former baseball commissioner Fay Vincent, who also served as president of Columbia Pictures. "It's too bad. There has to be a line drawn somewhere. I'm not sure where it is. The bases should be protected from this."

Baseball executives moved swiftly to defend the plan.

"Any criticism is misplaced," said baseball's president and chief operating officer Robert DuPuy, adding that the movie's logos on the bases will only be visible to fans in the upper decks and to TV viewers during the overhead shot. Nothing's been done to affect the play of the game."

The ads, about four inches long with the drawing of a spider's web, will appear on first, second and third base and the pitcher's rubber. Home plate will be covered by a commemorative ad that will be removed before the game starts. The on-deck circles also will be covered with a much larger ad.

Advertising, or more specifically "product placement," has become an increasing part of the sports scene for the last several decades, but it appears to have picked up momentum in recent years as sports teams and athletes search for new sources of revenue.

Lou Graham launched the product placement movement on professional golfers when he began wearing an "Amana" hat for the appliance maker during a tournament in the 1960s. The NHL began allowing four sponsorship logos on its ice about 10 years ago. The NFL receives tens of millions a year for allowing its coaches to wear Motorola-branded headsets on the sideline and allowing Gatorade to display its unmistakable containers and cups there as well. The NBA sells prominent courtside advertising that revolve underneath the scorer's table throughout the game, although signage is not allowed on the court itself. The protective padding on the supports under each basket are also used for advertising.

Professional sports leagues in Europe have long allowed sponsors to advertise on its players. Manchester United has a multimillion-dollar deal with Vodafone that allows the telecommunications giant to advertise directly on the English soccer team's uniforms.

But no sport seems to have triggered the recent onslaught in on-field, on-court and on-player product placement as much as NASCAR, the hugely successful stock-car racing circuit. Everything from the racing cars to the fire-retardant jump suits that drivers wear are covered in corporate logos.

"I could pay you $1 million to try and not run into our name at a NASCAR race and you would lose," said Audrey Schaefer, a spokeswoman for Reston-based Nextel Communications. Nextel paid $700 million over 10 years to be NASCAR's official sponsor.

Schaefer said Nextel doesn't worry whether the company offends fans with its massive approach to advertising because of stock-car racing's tradition of sponsorship bombardment. But critics deride the marketing tactics as dehumanizing and insulting to fans.

"Fans are gouged, mistreated and . . . now they are going to have to watch baseballs with ads on them," said consumer advocate Ralph Nader. "Where does it end?"